Democratic candidate Mark Kelly’s Senate campaign came under fire Thursday after a conservative media site found that a deputy press secretary directed a profane tweet at law enforcement in Chicago last summer.

The campaign’s press office said it was unaware of the tweet until the criticism started Thursday. Last August, Timothy Jose L’Heureux used an expletive in calling out what he called "worthless pigs” in response to a video showing Chicago police officers clashing violently against demonstrators. 

In response to questions from KJZZ News, Kelly’s staff said the candidate is the son of two police officers and that he found the tweet unacceptable.

The staffer apologized for his tweet and has since locked down his account and deleted the post.